PHNOM PENH, Cambodia (AP) — Cambodia’s highest court, the Constitutional Council, on Tuesday began a review of the contested results of last month’s general election, leaving open a small possibility that it will resolve the opposition’s claims of unfairness.

The review comes after the state National Election Committee on Saturday rejected all 19 complaints filed by political parties against the results of the July 28 polls. The official results would give the ruling Cambodian People’s Party 68 seats in the 123-seat National Assembly, and 55 to the opposition Cambodia National Rescue Party.

The opposition has threatened massive street demonstrations if its complaints over the election process are not dealt with by an impartial independent panel. A panel has been established, but seems to be making no progress. The Constitutional Council has up to 20 days to complete its review.

The opposition said the street protests would be a “last resort,” but the threat raised fears of political violence, especially because the government responded by deploying troops and armored vehicles in the capital. Prime Minister Hun Sen, Cambodia’s leader for 28 years, has a reputation of dealing harshly with his opponents.

The official popular vote count shows the Cambodian People’s Party receiving 3,235,969 votes and the Cambodia National Rescue Party 2,946,176, with six other parties failing to accrue enough votes to win any assembly seats.

The opposition says it actually won 63 assembly seats. Even the 55 conceded by the ruling party represents a substantial increase on the 29 seats it held in the last assembly.

The main complaint of the opposition concerns the voter registration process, which it alleges led to possibly more than 1 million people not being properly listed and therefore unable to vote. The complaint has been supported by several nonpartisan poll watching groups.